ADVANCES AND PROBLEMS IN THE STUDY OF 

 GENERATION AND INHERITANCE 



BY OSKAR HERTWIG 

 (Translated from the German by Dr. Thomas Stotesbury Githens, Philadelphia.) 



[Oskar Hertwig, Regular Professor of General Anatomy and History of Evolution 

 since 1888; and Director of the Anatomical-biological Institute since 1888, 

 University of Berlin, b. Friedburg, Hessen, April 21, 1849. Student of Medicine, 

 Jena, 1868; Zurich, 1869; Jena, 1870; Bonn, 1871-72; M.D. Bonn, 1872; Ph.D. 

 Bononiensis, 1888. Privy Councilor of Medicine, 1897; Regular Professor of 

 Human Anatomy and Director of Anatomical Institute, Jena, 1881-88. Member 

 of the Physio-Medical Society, Erlangen; Royal Academy of Science, Berlin; 

 Academy of Sciences, Munich, Stockholm, Copenhagen; and many other scientific 

 and learned societies. Author of Text-Book of the History of Evolution of Man 

 and of Vertebrates; The Elements of the Science of Evolution; Timely and Disputed 

 Questions of Biology; and numerous other works and memoirs on anatomy.] 



FROM the time of Greek science until our own day, no other pro- 

 blem has interested the scientific investigator as much as that of 

 animal development. Still after many centuries, difficulties remain 

 that appear insurmountable to human powers. This is especially 

 true of the secret problem of generation. In earlier centuries, the 

 old anatomists with their incomplete methods of investigation could 

 not win true knowledge, which, however, they sought to replace by 

 hypotheses, which were generally without permanent value, and 

 sprang from the earth like mushrooms. At the end of the seven- 

 teenth century more than 300 could be enumerated, and when the 

 famous physiologist Haller brought together the work of several 

 centuries, in his great handbook of physiology, he commenced the 

 chapter on generation with the complaint, which was certainly 

 justified at that time, " Ingratissimum opus, scribere de iis, quae 

 multis a natura circumiectis tenebris velata, sensuum luci inaccessa 

 hominum agitantur opinionibus." 



The century of natural sciences, the nineteenth century, was the 

 first to lay a scientific basis for the study of generation, as well as 

 for that of so many branches of natural science. Since then such 

 great advances have been made, that if Haller should, in our day, 

 begin again to write the chapter on generation, he would certainly 

 term it, in contrast to the year 1746, an " opus gratissimum. " 



For is it not a pleasant task to follow the way in which the torch 

 of science has constantly more brightly illumined a realm, which for 

 many centuries was looked upon as one of the most hidden; also 

 how, on the successfully trodden way, the new discoveries have, with 

 certainty and regularity, been crystallized around the already deter- 

 mined truth ? Therefore, I may surely count upon a general interest 



